Thermosensitive instrument



July 5, 1938. R. E. OLSON El AL 2,123,019

' THERMOSENSITIVE INSTRUMENT Filed D80. 24, 19 35 INVENTO RA YMOND E. OLSON KENNETHL'TATE ORNE Patented July 5, 1938 UNITED STATES PATENT OFFICE 2,123,019 THERMOSENSITIVE INSTRUMENT I York Application December 24,1935, Serial No. 56,124 ifolaim. (01. 297-3) This invention relates to thermosensitive instruments. v

In the manufacture of various products, particularly rayon, it is necessary to shred and mix the raw materials preferably at a predetermined temperature. Since the mentioned raw materials are relatively poor conductors of heat, it has been difficult to obtain an accurate determination of the average temperature thereof. Furthermore, the bulbs of temperature indicating or regulating instruments formerly employed in connection with shredding and mixing operations have been of such construction and have been mounted in such a manner that there was a high percentage of injury to them during use.

In accordance with the main feature of the present invention a novel thermosensitive system is provided in which the sensitive element or bulb thereof extends across a receptacle so that the bulb has a large surface to be used in sensing the average temperature of the processed material in the receptacle, and the bulb is anchored in the opposite walls of the receptacle so that the danger of bulb injury or breakage is greatly reduced.

A further feature of the invention relates to a bulb of a thermosensitive tube system which extends parallel to the axis of the rotating blades of a shredder as close as possible to the saddle so that the bulb is continuously subjected to the hottest part of the shredded material.

These and other features of the invention will appear from the detailed description and claim when taken with the drawing in which Fig. 1 is a vertical longitudinal section taken through a shredder, together with a temperature indicating instrument, the bulb of which extends lengthwise of the receptacle; Fig. 2 is a vertical section taken substantially on the line 22 of Fig. 1; Fig. 3 is. a longitudinal section taken through the bulb of the thermosensitive instrument, fragments of the opposing walls of the receptacle being shown to illustrate the mounting of the bulb therein; Fig. 4 is a cross section of the bulb taken substantially on the line 44 of Fig. 3; and Fig. 5 is likewise a different cross section of the bulb taken on the line 5-5 also of Fig. 3 indicating the various details of construction of the bulb.

In the drawing, 5 generally designates a shredder including an open-topped receptacle 6 having a removable cover I. The outer wall of the receptacle and cover are provided, in accordance with the usual practice, with suitable heatlagging material (not shown), while the walls of the receptacle are hollow as indicated at 9, to contain a circulating cooling medium introduced from' a circulating system (not shown) which medium is controlled either manually or automatically by means (not shown) to prevent any deviation in temperature which is indicated by the thermosensitive instrument R. The instrument herein illustrated is represented as being a temperature indicator, but it will be understood that it can be a combined indicator and regulator, in which case the regulating portion thereof will control the flow of the circulating cooling medium. Within the receptacle there is provided a metal saddle II having two toothed surfaces l2 and I3 with which the blades [4 and I5 of the cutters respectively cooperate. In accordance with the usual practice, these blades are arranged to rotate alternately by means (not shown), first in one direction and then after a predetermined interval in the reverse direction as indicated by the arrows.

The mentioned instrument R includes a bulb I6 connected through a. capillary tube l! to a Bourdon spring [8, constituting a tube system which is filled with a thermosensitive medium (not shown). It will be understood that the free end of the Bourdon spring is connected by a link [9 to a pen arm 20 pivoted at 2| on the instrument frame. The lowerend of the pen arm carries a stylus in operative relation to a graduated chart 22 which is arranged to be rotated by a suitable clock mechanism (not shown).

In the past, much difliculty has been encountered in determining the average temperature of the mass of material, such as cellulose, in the shredder owing to the relatively slow heat conduction through the material and owing to the relatively small area of prior bulbs. Furthermore, since prior bulbs have been supported at one end only, they have been subjected to breakage so that frequent replacement thereof has been necessary. In accordance with the principal feature of this invention, the bulb is mounted at its ends in openings in two of the opposite walls of the receptacle to extend the entire length of the receptacle as near as possible to the saddle l l. The bulb comprises a hollow tube or shell 23 of a length approximately equal to the distance between the opposite walls of the receptacle in which it is to be mounted. There is provided within the bulb a hollow core 24 serving to reduce the volume of the bulb and also to give it added strength. The core, at its left end, is separated from the inner wall of the tube 23 by a sleeve 25 making a tight-fit between the bulb and the core. The left end of the sleeve and the core are welded together to make a fluid-tight joint between these parts. An externally threaded collar 26 partially telescoped over the left end of the tube 23, is welded at 21 to the outer wall of the tube. The right end of the core is spaced from the inner wall of the bulb by a sleeve 28 tightly engaging the inner wall of the tube 23 and the core 24. This sleeve has a slab side 29 to permit the passage of the thermosensitive medium therethrough. The right end of the bulb is closed by a plug welded to the tube 23 and apertured to receive the capillary tube H which is welded as indicated at 30, to the plug. It will be noted that the plug is slightly spaced from the end of the core 24 and the sleeve 28 to afford a passage at the end of the core communicating with the passage formed by the slab side 29 of the sleeve. The right end of the bulb has an externally threaded collar 32 partially telescoped thereon and welded to the tube 23- at 33. The sleeves 25 and 28 fill only a portion of the space between the core and the inner wall of the bulb thereby afiording an elongated space 3! of restricted cross-section for the thermosensitive medium. However, the volume of the space 3| is much larger than that of the bulbs formerly used, for example, three times as large, so that the error introduced by the mechanical compression of the bulb is negligible.

In mounting the bulb in the receptacle, heat insulating bushings 34 and 35separate the walls of the receptacle from the collars on the ends of the bulb. Clamping nuts 36 and 31 engaging the collar 26, clamp the heat-insulating washers 38 and 39 against the faces of one wall of the receptacle to afford a tight joint. Similarly the clamping nuts 40 and M engage the collar 32 and with the heat insulating washers 42 and 43 make a liquid-tight joint with the opposite wall of the receptacle.

While the bulb has been illustrated in connection with a shredder, its use is not so limited, for it can be applied to various receptacles.

We claim:

A thermosensitive bulb including a shell, a plug closing one end of said shell, a capillary tube joined to said plug and having one end communicating with the interior of said bulb through said plug, a core within said shell, a sleeve located adjacent the last-mentioned end of said bulb and surrounding said core to space the same from the inner wall of said tube, said sleeve having a portion thereof spaced from said tube to define a passageway leading to said capillary tube, a second sleeve surrounding the other end portion of said core, said second sleeve being connected to said core and to said tube by a liquid-tight seal, an. externally threaded collar partially telescoped over each end of said shell and attached thereto, and at least one clamping nut making thread-ed engagement with each sleeve.

RAYMOND E. OLSON. KENNETH L. TATE. 

